The present invention relates to a propeller shaft assembly and, more particularly, to the attachment of a stub shaft and an inner race of a constant velocity joint which provides for increased bending stiffness.
Typically, a vehicle propeller shaft drivingly interconnects a transmission assembly and an axle assembly such that the torque produced by the transmission is transferred through the propeller shaft to the axle thereby driving one or more of the vehicle wheels. Connecting assemblies drivingly connect the ends of the propeller shaft to any number of components including but not limited to a transmission, a power transfer unit, a torque transfer device or an independently mounted axle.
Another type of propeller shaft includes multiple shafts or segments which are drivingly connected together and rotatably supported by a propeller shaft bearing assembly. The propeller shaft segments typically include a connecting assembly which operatively connects or links the two shaft segments of the propeller shaft and a center bearing which rotatably supports the connecting assembly. One known connecting assembly includes a forged stub shaft having a large diameter shoulder on one end and a small diameter body with an external spline on the other end for insertion into the inner race of a constant velocity joint. The large diameter of the forged stub shaft is typically welded to the tube of the propeller shaft.
Many constant velocity joints are operable to allow an angulation between the axis of rotation of the stub shaft and the axis of rotation of the constant velocity joint outer race of 10 degrees or more. To achieve the maximum angulation of the constant velocity joint, the body portion of the stub shaft has a small outer diameter that is substantially smaller than outer diameter of the inner race.
The bending stiffness of a propeller shaft assembly is greatly influenced by the minimum diameter of the shaft and the length that the relatively small diameter extends from the loading points. Accordingly, the known forged stub shaft having a small diameter body may compromise the overall bending stiffness of the propeller shaft and, the longer the reduced body diameter extends, the lower the bending stiffness. It has been shown that the lower the bending stiffness, the more likely undesirable noise, vibration and harshness will be produced. Furthermore, existing propeller shaft assemblies may include a greater mass than necessary for transmitting rotary loads. Accordingly, it is desirable to reduce noise, vibration and harshness and reduce the weight of the propeller shaft assembly. Therefore, a need exists for an improved propeller shaft assembly having an increased bending stiffness and reduced mass.
The present invention includes a propeller shaft assembly having a substantially cylindrical hollow propeller shaft, a constant velocity joint having an inner race and an outer race drivingly interconnected by a plurality of balls, and a stub shaft. The stub shaft has a first end fixed to the propeller shaft and a second end drivingly coupled to the inner race. The second end includes a portion positioned adjacent to the inner race. The portion includes an outer diameter greater than an outer diameter defined by the interface between the inner race and the plurality of balls.
According to another aspect of the invention, the propeller shaft assembly includes a substantially cylindrical hollow propeller shaft, a constant velocity joint having an inner race and an outer race drivingly interconnected by a plurality of balls, and a hollow stub shaft. The hollow stub shaft includes a first open end fixed to the propeller shaft and a second open end drivingly coupled to the inner race.
These and other features, aspects and advantages of the invention will become apparent by reading the follow specification and by reference to the following drawings.